While the U.S. Postal Service strives to develop nonmail ventures to keep it afloat, its Ethiopian counterpart has found a novel side business, mining dreams of America.

The U.S. government issues green cards to 50,000 people world-wide each year by sheer luck of the draw. Nationals from countries that have sent few immigrants to the U.S., such as Ethiopia, are eligible to participate in the program, known as the Diversity Visa Lottery. Saturday marks the end of this year's 30-day entry period, during which millions across the globe rushed for a chance to win a green card.

In Ethiopia, where the lottery is mainly known as "DV" and Internet penetration is minuscule, the online-only entry process has generated a burst of business. Internet cafes have profited, and so has the Ethiopian Postal Service, which collects a service fee starting at 10 Ethiopian birr, or 57 cents, for each online entry it processes.

Tsehay Wondim, who owns an Internet kiosk with five computer terminals, normally charges one birr for every five minutes of Web surfing. "During DV season, I double my business," she says. A tattered white sheet drops from the ceiling to serve as background for the requisite digital photo, which she takes of each entrant as part of the 10 birr she charges per submission.

Lottery season is the busiest time for the one-window postal branch at the university, says clerk Dinkensh Mekonen.

"Everybody participates," she said, as she reviewed a customer's handwritten form, collected payment and handed him a green receipt. "Even I do."

The U.S. government doesn't charge participants to enter the draw. But in 2010, the Ethiopian Postal Service earned two million birr (about $350,000) in revenue on its 100,000-birr investment in the lottery, which its officials call "the project."

"DV is such a big business," said Belesti Esubalu, the postal service's marketing manager.

In 2010, according to the U.S. State Department, 785,318 Ethiopians and their dependents submitted entries, and at least as many are anticipated this year. According to local lore, only the fervor for English soccer's Premier League dwarfs the passion for the DV lottery in Ethiopia, a country with a per capita GDP of $1,000 and a 25% unemployment rate among those ages 15 to 24.

Internet kiosks are festooned with photos of President Barack Obama and banners that proclaim in big red, white and blue letters, "DV 13," for 2013, the year in which this season's winners will receive their green cards.

Ethiopia's postal service doesn't advertise the lottery because the country's government frowns on encouraging emigration, postal officials say. Not that the lottery needs advertising.

"When it's DV season, Ethiopians everywhere are talking about it," says Zerihun Seyoum, a well-known native artist who has a painting he called "Diversity Visa."

This year at the capital's central post office, "the project" took over an entire wing. Hundreds of workers toiled on a recent day in three large rooms processing lottery entries.

The service used to play only the traditional letter-carrier role during the lottery, delivering handwritten entry forms to Internet cafes, which entered data from the forms onto the State Department's official "electronic diversity visa entry form." But three years ago, the post office started to offer its own "comprehensive, in-house service," said Mr. Esubalu.

Preparation begins months before the lottery is on most Ethiopians' minds. In July, the service advertises lottery-related temporary jobs.

Eligible applicants must pass a test for typing accuracy and speed, says Yosef Gebrezeghabhir, the postal system's IT manager and a member of the project team. Accuracy accounts for 70% of an applicant's final score, because any discrepancy between information on an individual's electronic submission and actual documents, such as a birth certificate, can lead the U.S. State Department to disqualify a winner.

The post office charges 10 birr for the primary applicant and five birr per dependent listed on the same form. The post office can also create an email address, which the State Department requires, for an additional two birr.

"I've been saving for this," said Brhanu Arezaynie, a 19-year-old student at the university post office. The silversmith's son, who is entering for the first time, said the U.S. represents "good work, good money and good education."

To his completed handwritten application, Mrs. Mekonen, the clerk, attached Mr. Arezaynie's mugshot, to be scanned and attached to his electronic entry at the central post office.

Forms filled out by Mr. Arezaynie and other applicants arrive daily by the truckload at the central post office. On a recent Thursday, wagons of packets with applications were wheeled into a large room. One group of workers opened packets and separated forms from attached photos. Other teams scanned photos and entered personal data into the online forms.

As dozens of workers sat shoulder-to-shoulder at terminals, DV-13 lottery coordinator Hailegeoris Gemeda spot-checked the online forms for accuracy. He pointed proudly to a chart on the wall that showed workers' productivity the previous day. The champion was 22-year-old Hiwot Tilaun, who had completed 240 entries in her eight-hour shift.

In the lottery's final days, Miss Tilaun and her colleagues were set to work around the clock. The postal service predicts it will handle at least one-quarter of Ethiopia's submissions.

On May 1, a U.S. government computer in Kentucky will select 100,000 entries for green-card processing. Ultimately, 50,000 visas will be granted. Last year, 4,902 Ethiopians were winners.